This invention relates generally to bowling balls and more particularly to a novel bowling ball adapted to travel a curvilinear path and having a larger area of maximum hitting force than previously available balls. The invention also provides a method for making the novel and improved bowling ball.
Bowling balls used in competitive sports events must conform to specifications of the American Bowling Congress. The ball cannot weigh more than 16 pounds and must have a circumference of about 27 inches. The ball is provided with appropriately spaced finger holes for reception of the thumb, middle finger and an adjacent finger. These finger holes are drilled in the "top" of the ball. The top weight of the ball must be within three ounces of the bottom weight and the side weights must be within one ounce of each other. The more skillful bowlers roll the ball so that it enters the pin placement at angle with respect to the longitudinal axis of the bowling lane or alley. This requires that the ball be following a curved path as it strikes the pins and provides for maximum "pin carry". It is known that top weight, which provides a positive off-balance at the finger holes, assists the bowler in rolling a curve or hooked ball. The better bowlers repeatedly roll the first ball of a frame along substantially the same path with adjustments based on changing lane conditions. Theoretically the ball should strike the "pocket" each time at essentially the same angle with respect to the longitudinal axis of the pin placement and with the top weighted point of the ball striking the pins. If the roll is perfectly executed, all ten pins will be knocked down on each roll. However, if there is a departure in form, the ball might not curve at the expected angle or might not rotate so that the pins are struck with the maximum impact.
The conventional bowling ball is provided with a top weight insert generally at the location of the finger holes. This is the point that should strike the pins for maximum effect. It has been proposed in U.S. Pat. No. 3,350,252 to provide this top weight by including in the core of a bowling ball a foam plastic insert spaced radially outwardly from the center of the external shell in the bottom of the ball. The point of top weight of the ball is marked on the surface so that finger holes can be properly located. The point of mass concentration of the ball will theoretically be the same from ball to ball if the location of the insert is the same. The foam insert has a disadvantage that it has an irregular surface of open cells and webbing between the cells. The polymerizable plastic mass used to mold the ball about the insert will enter the cells and produce an irregular interface between insert and ball body which along with the variation in density will result in an irregular distribution of weight. The net result will be that the point of mass concentration will vary from ball to ball. Such variance will be accentuated in lighter weight balls where larger foam inserts are required because of the larger exposed area.
A bowling ball having a solid top weight substantially less than a hemisphere placed in the top half of the ball closely adjacent to the midplane is disclosed in U.S. Pat. No. 3,865,369. The density of the insert is substantially greater than that of the body of the ball which makes it undesirably necessary to use a relatively low density resin for the body.
A bowling ball having a solid wood or metal insert disposed about the geometric center of the ball is disclosed in U.S. Pat. No. 575,128. This ball allegedly rolls noiselessly along the lane. A bowling ball having a shell enclosing a hollow center with the inner wall concentric with the outer surface of the ball is disclosed in U.S. Pat. No. 3,256,018. The shell is formed of a plurality of cast layers of resin. Such balls do not provide for maximum "pin carry" and are not designed to facilitate curving or hooking of the ball.
No matter what configuration or composition, all bowling balls, of which I am aware, are manufactured in a reusable, usually two-piece metallic mold. Such a procedure not only requires a great deal of capital expenditure for mass production purposes but also is susceptible to material waste due to leakage between the mold halves. If great enough, leakage may also result in a scrap ball because voids are formed beneath the surface of the ball. In addition, accelerated curing with microwaves is not feasible with a metallic mold since the microwave energy would be substantially absorbed by the metal itself.
Finally, in balls provided with top weights, usually what can be called the "aspect ratio" of the weight, that is, the ratio of its length to its width, is unity. While providing eccentricity, this concentration of weight can often provide an uneven noncentroidal rolling or "loping" which, if carefully analyzed, could be said to be rolling with periods of acceleration followed by periods of deceleration due to the momentum of the weight. Thus, it is desirable, if providing a top weight, to avoid this uneven rolling. Such noncentroidal rotation can be further complicated if the finger and thumb holes are not properly positioned in the ball. The driller of the ball cannot, by looking at the ball, always determine the precise location or orientation of the top weight. Usually this is accomplished by a balancing procedure which does not always lend itself to consistent results.